Darran Weiss, 23, sank twice before she finally bobbed to the surface last year as one of fashion's most promising swimwear designers. Her 50-piece collection, which is influenced by evening wear and combines unusual fabrics such as georgette with Lycra spandex, has earned the designer high praise. "She is the most innovative in the industry," says Robbyn Meringolo, buyer for New York's Bonwit Teller department store. Last summer Vogue cheered Darran's line for offering "everything from a simple suit to glamorous and ornamented swimwear."

Darran, who designed evening dresses with modest success in Washington while majoring in business administration at the University of Maryland, found the Capitol Hill crowd too conservative in its taste for clothes. So on graduation day in June 1980, she headed for New York where, she recalls, retailers "stepped on my toes and closed doors on my fingers."

After a month of that, Darran, whose father commutes to New York to help run a garment district showroom, returned home to Philadelphia. Soon a friend of her mother's introduced Darran to swimwear manufacturer Bill Myer. Six weeks later, with $23,000 borrowed from her parents, she had put together a line of bathing suits to show him. But when she returned to New York with it, she was rebuffed again. Determined, Darran took off for Fort Lauderdale, Fla., where her designs caught the eye of Saks Fifth Avenue executive Sandy Laveter. After selling to buyers in Atlanta, L.A. and Las Vegas, Darran stormed New York again, and this time took orders from Macy's, Henri Bendel and Bonwit's. Her collection is now in more than 100 stores, and this year Darran expects to gross $750,000, three times her total sales for 1981.

Darran's newest splash is a brightly colored Italian lifeguard suit that sports a small pocket with a whistle inside. Her most frivolous offering: a white azurene mink bikini. "It makes a small bust look big," quips Darran. But would anyone ever take a dip in it? "Sure," she says. "Minks swim too."